The invention relates generally to equipment for manufacturing paper containers and in particular to equipment for manufacturing paper bags. Specifically, the invention relates to feed mechanisms for feeding bag units or bags or partially manufactured bags, such as bag tubes or tube stock, to a subsequent manufacturing operation.
There are various types of feeding mechanisms in the prior art, some of which relate to the manufacture of paper products. An example in the prior art is U.S. Pat. No. 3,606,306 for which the present inventor was a co-inventor.
In the aforementioned bag feeder of the prior art, a stack of bag tubes is fed on to a ferris wheel type conveyor that elevates the series of stacks of bags to an elevated pick-up mechanism at the top of the machine. The elevated pick-up mechanism then selects one bag at a time and feeds them into a double belt conveyor for a susequent operation. In references herein, the terms "bag unit", "bag", "bag tube", and "bag stock" are interchangeable.
The problems encountered with bag feeders of the prior art are several: the machine operation, because of its inherent operation, is noisy; the "shingling" of stacks of bags on the conveyor are in reverse position and must be lifted at the trailing end in order to put in the next stack; the old method of overlapping stacks requires a longer conveyor system; the old method of overlapping stacks causes problems of stack slippage at the transfer point; bag "tubes" with large pleats are difficult to pick up with a suction system; the machine must operate at a slower speed than the machine's actual capability for moving bags; placing stacks of bags in the vertical type conveyor of the feeder is hazardous, because it is done manually; and other related problems.
In the present invention the aforementioned problems as well as other are eliminated. In the present invention the bag "tubes" may have plain return sides or gusseted sides folded flat, the "tubes" may be single wall or multiwall paper stock, the pick-up mechanism can handle more complex bag "tubes," the top of a packet of bag "tubes" in a stack (called a "hand" in the trade) is maintained at pick-up level for the suction cups and will adjust quickly if a "hand" is smaller than normal size, the "hands" of bag tubes may be loaded directly onto the conveyor more quickly without interference from the prior "hand," the horizontally operating mechanism is quieter than the vertically operating mechanism of the prior art, and the transfer of a "hand" of bag tubes from the conveyor to the feeding mechanism is rapid and positive. There are other advantages of the present invention over the prior art that will be obvious as the details of the invention are described. References herein to "packets of bags", "stacks of bags," and " bulk bags" are interchangeable.
It is to be noted that in the present invention there are three distinct structures for three distinct operations that take plate: an accumulating and indexing means for accumulating a series of stacks of bags and on signal indexing them forward; a receiving and cavity means for receiving a stack of bags indexed forward and maintaining the stack at a level for further dispensing; and a dispensing means for dispensing the bags one at a time for a subsequent operation.
Regarding the aforementioned accumulating and indexing means, there are two major types of structure. One type of structure is a conveyor type, such as a belt conveyor, on which a series of bags can be accumulated in shingle-like arrangement and then indexed forward a predetermined distance so that one stack of bags, the most forward stack, is deposited in the receiving cavity means each time the signal is received to index forward one movement. The other type of structure is a rack type, on which a series of stacks of bags are accumulated in pocket-like rack segments in shingle-like arrangement and then indexed forward a predetermined distance so that one stack of bags, in the most forward pocket-like position, is deposited in the receiving cavity means each time the signal is received to index forward one movement; and in a specified subsequent series of movements the rack is reset so that all other stacks of bags are effectively indexed forward the equivalent of one space.
Regarding the shingling arrangement of bags, in the prior art the shingling was a negative arrangement and in the present invention the shingling is a positive arrangement. In negative shingling, the trailing edge of the last stack of bags on the accumulating and indexing means is lifted, and the leading edge of the stack of bags being loaded on to the accumulating means is shoved under (shingled under) the aforementioned trailing edge of the stack of bags on the accumulating means. In positive shingling, the leading edge of the stack of bags being loaded is simply laid on top of the trailing edge of the preceding stack of bags.
In the conveyor type of accumulating means, and particularly when using negative shingling, the stack of bags have a tendency to slip or slide and become disoriented. In the rack type of accumulating means the aforementiond pocket-like rack segments provide an effective means for maintaining the stack orientation, permits the effective use of positive shingling, and is so configured that a portion of the pocket-like rack segment acts as a "pusher" during the indexing phase.
The rack type accumulating and indexing means and positive shingling is the preferred embodiment.
It is, therefore, an object of the invention to provide a bag feeder mechanism that is easy to load.
It is another object of the invention to provide a bag feeder mechanism that has a positive transfer forward at a high rate of speed to the operating position.
It is also an object of the invention to provide a bag feeder mechanism that will handle flimsy bags readily.
It is still another object of the invention to provide a bag feeder mechanism that will handle pleated or gusseted bags readily.
It is yet another object of the invention to provide a bag feeder mechanism that uses the leading portion of the following "hand" of bag units to hold down the rear or trailing portion of the preceding "hand" on the receiving cavity elevator mechanism while the pick-up mechanism of the dispensing means lifts the leading edge of the bag being dispensed.
It is also another object of the invention to provide a bag feeder mechanism that will prevent waste of the high speed potential of the feeder in relation to the lower speeds of the subsequent operations.
Further objects and advantages of the invention will become more apparent in the light of the following description of the preferred embodiments.